Expression of genes encoding neuropeptides and enzymes in the brain, with emphasis on the hypothalamus, are being studied. We have isolated the rat oxytocin gene and are continuing our transgenic mice experiments (that enabled expression of oxytocin in a tissue and physiologically specific fashion) with promoter-mutated transgenes. Several lines are being bred to homozygosity now to study physiological regulation of the transgenes in comparison with the endogenous counterpart. We have also been analyzing sites of action of vasopressin and oxytocin, both centrally and peripherally and during development, by in situ hybridization with probes for their receptors. We are attempting to "knock-out" the OT gene through homologous recombination. We are also studying the novel POU protein, RHS2 (Brain-4), whose full-length cDNA we previously cloned. We have mapped the sites of expression, including during development in the mouse, of the four class III POU proteins to further our understanding of their roles. We have also determined that the class III proteins interact with each other in western and two-hybrid assays and we are continuing our efforts to "knock-out" the gene through homologous recombination. Mapping of gene expression in the human hypothalamus continues: analysis of vasopressin and oxytocin, as well as of LHRH were published, and maps of the opioids have been submitted for publication. Maps of the tachykinins, corticotropin-releasing factor, somatostatin, and growth hormone-releasing factor are in progress. We are attempting to improve the technique of differential display to isolate the gene encoding the serotonin N-acetyltransferase from pineal and also to isolate hypothalamic-specific genes.